Field of the Invention
The present invention relates to wireless communication and, more particularly, to a method and an apparatus for receiving downlink frames in a WLAN (Wireless Local Area Network).
Related Art
The Wireless Next Generation Standing Committee (WNG-SC) of the IEEE 802.11 is an ad-hoc committee dealing with development of standard specifications of the next-generation WLAN technology in a long-term perspective.
At the IEEE meeting held on March 2013, Broadcom pointed out on the basis of the history of WLAN standardization that next-generation WLAN specifications following the IEEE 802.11ac should be discussed within the first half of the year of 2013, where the effective term of the IEEE 802.11ac standard is ended. Agreeing with the needs for the next-generation technology and standardization thereof, the WNG-SC has approved the motion for forming a study group for the next-generation WLAN at the IEEE meeting held on March 2013.
The technical scope of the IEEE 802.11ax mainly dealt with in the study group for the next-generation WLAN which is called the IEEE 802.11ax or High Efficiency WLAN (HEW) includes: 1) improvement of the 802.11 PHY (Physical) layer and Medium Access Control (MAC) layer at the frequency bands of 2.4 GHz, 5 GHz, and so on; 2) improvement of spectrum efficiency and area throughput; and 3) improvement of performance in indoor and outdoor environments such as an environment with interference sources, a dense heterogeneous network environment, and an environment with high user loads. A use-case scenario mostly used in the IEEE 802.11ax assumes an environment populated with a large number of Access Points (APs) and stations (STAs), and the IEEE 802.11ax is concerned with technologies capable of improving spectrum efficiency and area throughput under such an environment. In particular, the IEEE 802.11ax has an interest in improving actual performance in outdoor environments traditionally not having been dealt with in the existing WLAN specifications, as well as performance improvement in indoor environments.
The IEEE 802.11ax has great interests in such scenarios as those including wireless office, smart home, stadium, hotspot, or building/apartment, and on the basis of the corresponding scenarios, technical specifications capable of improving system performance in an environment populated with a large number of APs and STAs are being discussed.
It is expected that the IEEE 802.11ax will be more actively involved in the discussion about improvement of system performance in an Overlapping Basic Service Set (OBSS) environment, performance enhancement in an outdoor environment, and cellular off-loading than performance enhancement of a single link for one Basic Service Set (BSS). Such direction of the IEEE 802.11ax indicates that the next-generation WLAN technology is going to have technical specifications the scope of which overlaps with that of mobile communication technology. Taking into account the current situation where mobile communication and WLAN technologies are being investigated together in the areas of small cell and Direct-to-Direct (D2D) communication, technical and entrepreneurial fusion of the next-generation WLAN and mobile communication will be conducted more actively.